BOLETÍN DE INVESTIGACIONES MARINAS Y COSTERAS

Año 2006 - Volumen 35 Santa Marta - Colombia ISSN: 0122-9761 Instituto de Investigaciones Marinas y Costeras José Benito Vives De Andréis Vinculado al Ministerio de Ambiente, Vivienda y Desarrollo Territorial BOLETÍN DE INVESTIGACIONES MARINAS Y COSTERAS (Bulletin of Marine and Coastal Research)

BOLETIN DE INVESTIGACIONES MARINAS Y COSTERAS (Bulletin of Marine and Coastal Research) (ISSN 0122-9761) La revista científica BOLETIN DE INVESTIGACIONES MARINAS Y COSTERAS, premiada por COLCIENCIAS como la mejor publicación de su género en Colombia en 1997, y clasificada dentro de Publindex (COLCIENCIAS) como revista indexada en categoría A2 en el año 2005, considera para su publicación trabajos inéditos sobre cualquier tópico de investigación en el mar o en ambientes acuáticos de la zona costera, realizados en las áreas tropicales y subtropicales de América. Es editada y publicada en un volumen anual desde 1967 por el INSTITUTO DE INVESTIGACIONES MARINAS Y COSTERAS JOSE BENITO VIVES DE ANDRÉIS (INVEMAR). Hasta el volumen 8 llevó el nombre de Mitteilungen aus dem Instituto Colombo-Alemán de Investigaciones Científicas Punta de Betín y entre los volúmenes 9 y 24 se denominó Anales del Instituto de Investigaciones Marinas y Costeras. La revista se distribuye en cerca de 40 países de los cinco continentes, preferiblemente por el sistema de canje. Las instrucciones para la preparación y envío de manuscritos se encuentran en las últimas páginas de este volumen y en el portal de internet www.invemar.org.co/boletin. Director INVEMAR: Francisco Arias I., INVEMAR, Colombia Director de la revista: Jesus A. Garay, M Sc., INVEMAR, Colombia Editor Responsable, Vol. 35: Mario Rueda, Ph.D., INVEMAR, Colombia Comité Editorial: Arturo Acero, Ph.D., Universidad Nacional de Colombia - CECIMAR, Colombia Maribeb Castro-González, Dr. en Oceanografía, U. del Tolima, Colombia Guillermo Díaz-Pulido, Ph.D., U. del Magdalena - INTROPIC, Colombia Juan Manuel Díaz, Dr.rer.nat., Instituto Alexander von Humboldt, Colombia Guillermo Duque, Ph.D., U. Nacional de Colombia, Sede Palmira, Colombia Andrés Franco, Ph.D., Universidad de Bogotá Jorge Tadeo Lozano, Colombia Jesus A. Garay, M Sc., INVEMAR, Colombia Jaime Garzón-Ferreira, M Sc., INVEMAR, Colombia Diego L. Gil-Agudelo, Ph.D., INVEMAR, Colombia Ángela Inés Guzmán, Dr. en Oceanografía, U. Nal de Colombia, Sede Palmira Mónica Puyana, Ph.D, Universidad de Bogotá Jorge Tadeo Lozano, Colombia Mario Rueda, Ph.D., INVEMAR, Colombia Oscar David Solano, M Sc., INVEMAR, Colombia Yves-François Thomas, Dr., Especialista Geografía, Université Paris, Francia Asistente del Comité Editorial: Isabel Cristina Chacón Gómez, Biol., INVEMAR, Colombia Comité Científico (Evaluadores), Vol. 35: Arturo Acero, Ph.D Pedro Alcolado, Ph.D Carolina Bastidas, M Sc. Jacobo Blanco, M Sc. Néstor Hernando Campos C., Dr.rer.nat Franklin Carrasco, Ph.D. Guillermo Diáz-Pulido, Ph.D. Juan Manuel Díaz, Dr.rer.nat Guillermo Duque, Ph. D. Felipe Alejandro Estela Uribe, Biol. Universidad Nacional de Colombia - CECIMAR, Colombia Instituto de Oceanología, Cuba Universidad Simón Bolívar, Venezuela INVEMAR, Colombia Universidad Nacional de Colombia - CECIMAR, Colombia Universidad de Concepción, Chile Universidad del Magdalena - INTROPIC, Colombia Instituto Alexander von Humboldt, Colombia Universidad Nacional de Colombia, Sede Palmira, Colombia CALIDRIS, Colombia

Andrés Franco, Ph. D. Jesús Garay Tinoco, M Sc. Jaime Garzón-Ferreira, M Sc. Alfredo Gómez Gaspar, M Sc. Diego L. Gil-Agudelo, Ph.D. Georgina Guzmán Ospitia, Dr. Ciencias Geológicas (Cand.) Janet Kübler, M Sc. Oscar Miguel Lasso-Alcalá, Esp. Zoología Agrícola Rafael Lemaitre, Ph.D. Maggy Maud Nugues, Ph.D. Jorge Enrique Páramo Granados, M Sc. Roberto Pérez Castañeda, Ph.D. Mónica Puyana, Ph.D. Shawna Reed, Ph.D. Iván Rey, Biol. Mar. Mario Rueda, Ph.D. Miguel Angel Ruiz Zárate, Ph.D. Juan Armando Sánchez, Ph.D. Adriana Santos Martínez, M Sc. Christine H. L. Schönberg, Ph.D. Amber Shawl, M Sc. Oscar David Solano, M Sc. Frank Garfield (Gary) Stiles Hurd, Ph.D. Yves-François Thomas, Dr. Especialista Geografía Ana María Umaña Villaveces, Biol. Ángel Valdés, Ph. D. Robert van Woesik, Ph.D. Bernd Werding, Prof. Dr.rer.nat. Universidad de Bogotá Jorge Tadeo Lozano, Colombia INVEMAR, Colombia INVEMAR, Colombia Museo Marino de Margarita & Universidad de Oriente, Venezuela INVEMAR, Colombia INVEMAR, Colombia California State University, Estados Unidos Fundación La Salle de Ciencias Naturales, Venezuela National Museumof Natural History, Smithsonian Institution, Estados Unidos University of North Carolina, Estados Unidos Universidad del Magdalena, Colombia Universidad Autónoma de Tamaulipas, México Universidad de Bogotá Jorge Tadeo Lozano, Colombia College of Applied Biology of British Columbia, Canadá Universidad de Bogotá Jorge Tadeo Lozano, Colombia INVEMAR, Colombia Colegio de la Frontera Sur, Dpto. de Ecología y Sistemática Acuáticas, México Universidad de los Andes, Colombia Universidad Nacional de Colombia ñuncsa, Colombia Inst. of Biol. and Env. Sci., Zoomorphol. and Systematics, Alemania Harbor Branch Oceanographic Institution, Estados Unidos INVEMAR, Colombia Universidad Nacional de Colombia, Colombia Université Paris, Francia Instituto Alexander von Humboldt, Colombia Natural History Museum of Los Angeles, Estados Unidos Florida Institute of Technology, Estados Unidos Justus Liebig Universität, JLU, Alemania Foto portada: Oscar David Solano Canje: Centro de Documentación, INVEMAR; Colombia (E-mail: bibliote@invemar.org.co) Distribución y suscripciones: Comité Editorial, Boletín de Investigaciones Marinas y Costeras, INVEMAR. A.A. 1016. Cerro Punta de Betín, Santa Marta, Colombia. E-mail: boletin@invemar.org.co Página web: www.invemar.org.co Boletín en línea: www.invemar.org.co/boletin Diagramación y montaje electrónico: John Aref Khatib P. Impresión: Grey Ltda. Bogotá D.C.-Colombia

BOLETÍN DE INVESTIGACIONES MARINAS Y COSTERAS (Bulletin of Marine and Coastal Research) Registrado en ASFA, Biological Abstracts, BIOSIS PREVIEWS, Geobase, Periodica, Zoological Record, Latindex, Publindex y Scielo-Colombia 35 Instituto de Investigaciones Marinas y Costeras José Benito Vives De Andréis Vinculado al Ministerio de Ambiente, Vivienda y Desarrollo Territorial Santa Marta, Colombia, 2006

CONTENIDO - CONTENTS C.B. García and G. Díaz-Pulido Dynamics of a macroalgal rocky intertidal community in the Colombian Caribbean [Dinámica de una comunidad macroalgal del intermareal rocoso en el Caribe colombiano]...7 A.I. Guzmán-Alvis, P. Lattig and José A. Ruiz Spatial and temporal characterization of soft bottom polychaetes in a shallow tropical bay (Colombian Caribbean) [Caracterización espacial y temporal de los poliquetos de fondos blandos en una bahía tropical (Caribe colombiano)]...19 E. Cancio Mozo, J.C. Narváez Barandica y J. Blanco Racedo Dinámica poblacional del coroncoro Micropogonias furnieri (Pisces: Sciaenidae) en la Ciénaga Grande de Santa Marta, Caribe colombiano [Population dynamics of the coroncoro fish Micropogonias furnieri (Pisces: Sciaenidae) from the Ciénaga Grande de Santa Marta, Colombian Caribbean]...37 G. Bernal, A. Velásquez, I. Vargas, A.C. Agudelo, C.A. Andrade, J.G. Domínguez, C. Ricaurte y G. Mayo Variabilidad de los aportes a los sedimentos superficiales durante un ciclo anual en los bancos de Salmedina [Sediment supply variability during an annual cycle in Salmedina Reef Banks]...59 N. Manrique-Rodríguez, S. Bejarano-Chavarro y J. Garzón-Ferreira Crecimiento del abanico de mar Gorgonia ventalina (Linnaeus, 1758) (Cnidaria: Gorgoniidae) en el área de Santa Marta, Caribe colombiano [Growth of sea fan Gorgonia ventalina (Linnaeus, 1758) (Cnidaria: Gorgoniidae) in the Santa Marta area, Colombian Caribbean]... 77 J. Arias, S. Zea, F. Newmark y M. Santos-Acevedo Determinación de la capacidad antiepibiótica de los extractos orgánicos crudos de las esponjas marinas Cribrochalina infundibulum y Biemna cribaria [Antifouling capacity determination of crude organic extracts from the marine sponges Cribrochalina infundibulum and Biemna cribaria]...91 A. Acero P., A. Polanco F. y J. Garzón-Ferreira Coexistencia de las dos especies de cachorreta (Pisces: Auxis) en la región de Santa Marta, Colombia [Coexistence of the two species of Auxis (Pisces) in the Santa Marta region, Colombia]...103 M. López-Victoria and D.M. Rozo Model-based geomorphology of Malpelo Island and spatial distribution of breeding seabirds [Modelación geomorfológica de la Isla Malpelo y distribución espacial de aves marinas anidantes]...111 A.Osorno Arango y J.M. Díaz Merlano Explotación, usos y estado actual de la cigua o burgao Cittarium pica (Mollusca: Gastropoda: Trochidae) en la costa continental del Caribe colombiano [Exploitation, uses and current status of the West Indian topshell Cittarium pica (Mollusca: Gastropoda, Trochidae) along the Colombian Caribbean coast]...133 J.M. Guerra-García, T. Krapp-Schickel and H.G. Müller Caprellids from the Caribbean coast of Colombia, with description of three new species and a key for species identification [Caprélidos de la costa Caribe de Colombia, con la descripción de tres especies nuevas y una clave para la identificación de las especies]...149

C. Castro S., M. Monroy L. y O.D. Solano Estructura de la comunidad epifaunal asociada a colonias de vida libre del hidrocoral Millepora alcicornis Linnaeus 1758 en Bahía Portete, Caribe colombiano [Structure of the epifaunal community associated with free-living colonies of Millepora alcicornis Linnaeus 1758 in Portete Bay, Colombian Caribbean]...195 G. Duque y A. Acero P. Ración diaria y consumo de alimento de la población de Anchovia clupeoides (Pisces: Engraulidae) en la Ciénaga Grande de Santa Marta, Caribe colombiano [Daily ration and food consumption of the population of Anchovia clupeoides (Pisces: Engraulidae) in the Ciénaga Grande de Santa Marta, Colombian Caribbean]...207 O. H. Avila-Poveda and E.R. Baqueiro-Cárdenas Size at sexual maturity in the queen conch Strombus gigas from Colombia [Talla en madurez sexual del caracol pala Strombus gigas de Colombia]...223 NOTAS-NOTES C.B. García y N. Mendoza Aspectos de la biología de Portunus spinicarpus Stimpson, 1871 (Decapoda: Portunidae) en el Golfo de Salamanca, Caribe colombiano [Aspects of the biology of Portunus spinicarpus Stimpson 1971 (Decapoda: Portunidae) in the Gulf of Salamanca,Colombian Caribbean]...235 M.C. Díaz R., G. Bula Meyer, S. Zea y A. Martínez Ensayos de actividad biológica y ecología química de extractos orgánicos de algunas macroalgas del Caribe colombiano [Bioessays of biological activity and chemical ecology of organic extracts from some Colombian Caribbean macroalgae]... 241 D.P. Báez y N.E. Ardila Sobre la sinonimia entre Armina wattla Marcus y Marcus, 1967 y Armina muelleri (Ihering, 1886) (Gastropoda: Nudibranchia: Arminidae) [On the synonymy between Armina wattla Marcus & Marcus, 1967 and Armina muelleri (Ihering, 1886) (Gastropoda: Nudibranchia: Arminidae)]...249 A.Aguirre-Aguirre, N. Manrique-Rodríguez y N. Cruz-Castaño Primer registro del cangrejo Pilumnus pannosus Rathbun (Decapoda: Brachyura: Pilumnidae) para el Caribe colombiano [First record of Pilumnus pannosus Rathbun (Decapoda: Brachyura: Pilumnidae) from the Colombian Caribbean]... 255 J.C. Márquez, S. Zea and M. López-Victoria Is competition for space between the encrusting excavating sponge Cliona tenuis and corals influenced by higher-than-normal temperatures? [ Está la competencia por espacio entre la esponja excavadora incrustante Cliona tenuis y los corales, influenciada por temperaturas más altas de lo normal?]...259 F.A. Estela Aves de Isla Fuerte y Tortuguilla, dos islas de la plataforma continental del Caribe colombiano [Birds of Isla Fuerte and Tortuguilla, two islands on the continental shelf of the Colombian Caribbean]...267

Bol. Invest. Mar. Cost. 35 7-18 ISSN 0122-9761 Santa Marta, Colombia, 2006 DYNAMICS OF A MACROALGAL ROCKY INTERTIDAL COMMUNITY IN THE COLOMBIAN CARIBBEAN Camilo B. García 1 and Guillermo Díaz-Pulido 2 1 Universidad Nacional de Colombia, Departamento de Biología, CECIMAR/INVEMAR, Cerro Punta Betín, Santa Marta, Colombia. E-mail: cgarcia@invemar.org.co and cbgarciar@unal.edu.co 2 Universidad del Magdalena, Programa de Biología/INTROPIC, A.A. 1122, Santa Marta, Colombia. E-mail: guillermo.diaz@unimagdalena.edu.co ABSTRACT The macroalgal intertidal community at a tropical location (Punta de la Loma, Colombian Caribbean) was monitored at irregular intervals from 1992 to 1995. The highly diverse macroalgal community was relatively invariant in cover, taxa and biomass from small spatial scales (square centimeters). At larger spatial scales (square meters), however, there was a small but definitive seasonal pulse in dominance and composition. Sand intrusions over the rocky intertidal represents a strong disturbance reducing macroalgal cover during the dry season. Interannual variation was also detected. La Punta de la Loma appears to be influenced by the regional upwelling conditions. KEY WORDS: Dynamics, Macroalgal landscape, Intertidal, Colombian Caribbean. RESUMEN Dinámica de una comunidad macroalgal del intermareal rocoso en el Caribe colombiano. La comunidad macroalgal intermareal en una localidad tropical (La Punta de la Loma, Caribe colombiano), fue monitoreado a intervalos irregulares entre 1992 y 1995. La altamente diversa comunidad macroalgal presentó pocos cambios en cobertura, número de taxa y biomasa a la escala espacial de los cuadrantes (centímetros cuadrados). Sin embargo, a la escala espacial del paisaje (metros cuadrados) se detectó un pulso estacional en dominancia y composición, pequeño pero definido. Invasiones parciales de arena en la época seca constituyen fuertes eventos de perturbación que reducen la cobertura macroalgal. También se detectó variación interanual. La Punta de la Loma parece estar sujeta a las condiciones locales de surgencia. PALABRAS CLAVE: Dinámica, Paisaje macroalgal, Intermareal, Caribe Colombiano. Contribución No. 954 del Instituto de Investigaciones Marinas y Costeras INVEMAR y No. 295 del Centro de Estudios en Ciencias del Mar CECIMAR de la Facultad de Ciencias de la Universidad Nacional de Colombia Instituto de Investigaciones Marinas y Costeras - INVEMAR 7

INTRODUCTION The Caribbean coast of Colombia has a variety of marine ecosystems and habitats, such as coral reefs, seagrass beds, mangroves, and rocky shores. Most rocky shore area is abrupt, with steep slopes. However, broader (>1 20m) rocky intertidal platforms occur at some sites, harboring rich and abundant macroalgal communities. The dynamics of such communities have received little attention in the region and consequently, there is little information on the diversity, distribution, and variability of these algal assemblages (Díaz-Pulido and Díaz-Ruiz, 2003). It is widely known that intertidal communities display important changes in community structure at varying spatial and temporal scales. Temperate intertidal communities are highly seasonal and variable at different spatial scales (Underwood and Chapman, 1998; Underwood, 2000). Ecological processes such as herbivory, disturbance, predation, and recruitment, as well as oceanographic conditions, have been shown to structure intertidal communities (Menge and Branch, 2001). In the tropics, intertidal communities may also vary through time. However, the processes driving community dynamics are not well understood. Furthermore, it is not clear how algal communities vary at different spatial (cm 2 m 2 ) and temporal scales (within and between years). Studies on the dynamics of hard bottom communities in Colombia are rare. Most information available on macroalgal communities of the area has focused on spatial patterns of organization (Guillot and Márquez, 1978; Brattström, 1980; Márquez and Guillot, 1983; Díaz-Pulido and Díaz, 1997). Seasonal variations in algal communities in Colombia have been documented for coral reefs (Díaz-Pulido and Garzón-Ferreira, 2002) and rocky intertidals (García, 1992; Nuñez et al. 1999). However, changes at larger temporal scales (e.g. > 1 yr) have only been documented for upwelling coral reef communities (Rodriguez-Ramírez and Garzón-Ferreira, 2003) and there is no information about interannual dynamics of rocky intertidal communities. Our study is noteworthy in that algal communities were monitored over several years. In this study we describe temporal changes in the intertidal community and non-living elements (sand and bare rock), at La Punta de la Loma, Santa Marta area, Colombian Caribbean, from 1992 to 1995. STUDY SITE La Punta de la Loma (11º07ʼ31 N, 74º14ʼ00 W, approximately) is an exposed rocky platform encrusted with fossil corals and lithified mangrove roots (von Erffa and Geister, 1976), surrounded by sandy beaches. The platform provides wide horizontal 8 Boletín de Investigaciones Marinas y Costeras - Vol. 35-2006

intertidal surface favoring the establishment of a diverse algal community. The intertidal community at this location is dominated by benthic macroalgae, including algal turfs, foliose and erect seaweeds, and crustose coralline algae. Invertebrates such as corals, anemones, and sponges are common. The study focused on the macroalgal assemblage. There are two main climatic and oceanographic seasons in the region: the dry season, from December to April, and the rainy season, from May to November (Salzwedell and Müller, 1983). During the dry season trade winds blow from the northeast reach their highest intensity, and generates upwelling. During the calmer, rainy season, temperature rises and salinity decreases due to cessation of the upwelling and to increase of continental discharges. MATERIAL AND METHODS To investigate the temporal dynamics of the intertidal community and abiotic elements, we used 0.25 m 2 (50 x 50) PVC quadrats divided in 25 subquadrats. To determine macroalgal biomass variations (i.e., dry weight per species/quadrat), several randomly placed quadrats were denuded during February-March 1992 (8 quadrats), August 1992 (8 quadrats), February 1993 (8 quadrats), August 1993 (14 quadrats), February 1994 (4 quadrats) and November 1994 (4 quadrats). The relative abundance of intertidal elements (species of macroalgae, sand and bare rock) was estimated by point sampling using the same quadrats (described above) in September 1993 (58 quadrats), February 1994 (93 quadrats), April 1994 (16 quadrats), July 1994 (16 quadrats), September 1994 (16 quadrats), October 1994 (16 quadrats), November 1994 (16 quadrats), December 1994 (16 quadrats), January 1995 (15 quadrats), February 1995 (16 quadrats) and April 1995 (16 quadrats). Quadrats were haphazardly placed on the rocky shore but not exact spot was revisited in subsequent sampling dates. The intersections of the subquadrats within each quadrat were used as points, giving a total of 16 points sampled points per quadrat. As more than one species per point could be recorded due to superposition of species, frequently total points recorded exceeded 16 for a given quadrat. Because different number of quadrats were sampled at each time period, the abundance (number of points) of intertidal elements is expressed relative to sampling effort, i.e., relative to the total number of points recorded given a sampling date, and multiplied by 100 for easy numerical manipulations. Temporal trends were explored by means of nonmetric multidimensional scaling ordination (NMDS, Field et al. 1982) performed on a Bray-Curtis dissimilarity matrix. The null hypothesis that intertidal configuration was the same in the rainy (May to December regardless of the year of sampling) and dry (January to April regardless of the Instituto de Investigaciones Marinas y Costeras - INVEMAR 9

year of sampling) seasons, was tested by means of the ANOSIM procedure (Clarke and Green, 1988). Patterns of diversity and dominance were explored over time by means of k-dominance curves (Lambshead et al., 1983). As partial sand intrusion events were an important disturbance feature during the study, they were correlated with historical mean values for cumulative monthly photoperiod, discharges of the Magdalena river, rainfall, and wind velocity using Pearson correlations. A Kruskal-Wallis analysis of variance was carried out on species and abiotic elements present in all sampling dates, to test the null hypothesis that mean relative abundance between seasons was the same. December data was excluded to obtain equal number of sampling dates per season (five). Two-way analysis of variance was used to test the null hypothesis that mean (log) biomass per season was the same regardless of sampling year. In order to assess macroalgal dynamics at the quadrat spatial scale (square centimeters, in contrast to landscape spatial scale, square meters, which includes sand and bare rock) one-way analysis of variance was used to test the null hypotheses that relative abundance and number of taxa per quadrat were the same between months and seasons. Quadrats in which sand or bare rock appeared were therefore excluded from this analysis. RESULTS We found 53 macroalgal taxa on the rocky intertidal platform during the study (see Appendix 1 with systematic list), although only 33 were found and quantified within the quadrats (Table 1). The most abundant and most frequent species included the brown algae Padina gymnospora, the green Caulerpa sertularioides and the reds Acantophora spicifera, Laurencia papillosa and Gracilaria mamillaris (Table 1). Mean taxa richness per month was nearly equal between seasons (22.3±2.5 S.D. in the rainy season and 21.2±3.9 S.D. in the dry season). Ordination analysis (NMDS) showed that sampling dates from the dry season clustered separately from those of the rainy season, excepting April/1994 that appeared in the middle of the plot. Interannual variability was also indicated by the ordination position of sampling months sampled in different years (Figure 1). The null hypothesis that the configuration of landscape elements at La Punta de la Loma was similar for the dry and rainy seasons (ANOSIM procedure, p<0.05). Recorded landscape elements (i.e, algal taxa, sand and bare rock) were sorted into three groups: elements predominantly present in the dry season or in the rainy season and elements with no preference. Preference was arbitrarily assigned when cumulative abundance of a given element accounted for more than 60% in one season (excluding December to obtain a balanced design of equal number of months (5) per season). The 10 Boletín de Investigaciones Marinas y Costeras - Vol. 35-2006

Table 1. List of quantified macroalgal landscape elements at La Punta de la Loma, their cumulative relative abundance (arbitrary units) and frequency of appearance in sampling months. Taxa were ordered according to cumulative relative abundance. Landscape element Cumulative relative abundance Frequency Padina gymnospora 122.1 11 Caulerpa sertularioides 112.8 11 Sand 105.3 11 Acanthophora spicifera 99.3 11 Laurencia papillosa 89.8 11 Gracilaria mammillaris 88.1 11 Dictyopteris delicatula 78.4 11 Hypnea musciformis 59.8 11 Ectocarpaceae spp. 58.0 11 Gelidiella acerosa 57.2 11 Dictyota cervicornis 41.0 10 Ulva lactuca 24.2 11 Dictyota menstrualis 21.6 9 Bare rock 18.1 10 Polysiphonia ferulacea 15.5 7 Bryopsis pennata 13.6 6 Dictyota spp. 12.5 9 Bryopsis plumosa 12.3 8 Hypnea spinella 11.4 8 Sargassum spp. 11.3 8 Caulerpa mexicana 9.4 8 Solieria filiformis 6.0 5 Gracilaria blodgettii 4.9 7 Enteromorpha sp. 4.4 8 Spatoglossum schroederi 4.0 7 Gracilaria domingensis 3.7 3 Botryocladia occidentalis 3.4 2 Grateloupia sp. 2.7 4 Dictyota pfaffii 2.4 2 Wrangelia argus 2.2 4 Gracilaria sp. 1.2 2 Cladophora sp. 0.9 3 Bryothamnion seaforthii 0.3 3 Gracilaria damaecornis 0.2 1 Agardhiella ramosissima 0.2 1 groups formed are shown in Table 2. Approximately 1/3 of the elements were insensitive to seasonal change, whereas 1/3 were sensitive either to the dry or rainy seasons (Table 2). However, when Kruskal-Wallis one-way analysis of variance was used to test the null hypothesis of equal mean relative abundance per sampling month among seasons (excluding December again) for those elements that appeared in the 11 sampling dates, Instituto de Investigaciones Marinas y Costeras - INVEMAR 11

Figure 1. Nonmetrical multidimensional scaling (NMDS) ordination of sampling dates at La Punta de la Loma. Stress= 0.161. only sand and Caulerpa sertularioides showed significant differences (p<0.05). This finding suggested irregular expansions and contractions of the landscape elements month after month, i.e., high relative abundance variability. Nevertheless there was a definitive dominance reordering from one season to the other (Table 2). The macroalgal intertidal community was most diverse in October 1994, which historically has been the rainiest and calmest month of the year (see k-dominance curves, Figure 2). In contrast, in April 1995, which corresponds to the driest and windiest time of the year, the macroalgal landscape was less diverse (Figure 2). The pattern had exceptions though. For example, diversity in April 1994 could not be distinguished from diversity in October 1994. Macroalgal biomass varied significantly throughout the years of study, being higher during 1994 following 1992 and 1993 (Figure 3). Two-way analysis of variance revealed no significant differences between seasons nor season and year (p>0.05), but a significant difference between years (p<0.05). Tukey multiple comparisons resulted that total macroalgal biomass was significantly different (p<0.05) among the three years. Relative abundance of taxa per quadrat, i.e., at the quadrat spatial scale, was not different between seasons (p>0.05) but it was significantly different between months (p<0.05), with taxa in September 1993 significantly less densely packed than taxa in April 12 Boletín de Investigaciones Marinas y Costeras - Vol. 35-2006

Table 2. Macroalgal landscape elements by season (> 60% cumulative abundance in one season excluding December) arranged by dominance. *= more abundant and frequent elements in the study, see Table 1. Element Rainy Season Element Dry Season Padina gymnosporaz* > 60% Sand* >60% Caulerpa sertularioides* >60% Laurencia papillosa* >60% Acanthophora spicifera* 40-60% Dictyopteris delicatula* 40-60% Gracilaria mammillaris* 40-60% Gracilaria mammillaris* 40-60% Hypnea musciformis* >60% Caulerpa sertularioides* <40% Dictyopteris delicatula* 40-60% Acanthophora spicifera* 40-60% Laurencia papillosa* <40% Padina gymnospora* <40% Ectocarpaceae spp.* >60% Gelidiella acerosa* 40-60% Gelidiella acerosa* 40-60% Hypnea musciformis* <40% Dictyota cervicornis >60% Ectocarpaceae spp.* <40% Sand* <40% Dictyota menstrualis >60% Bryopsis pennata >60% Bare Rock >60% Ulva lactuca* 40-60% Ulva lactuca* 40-60% Dictyota sp. >60% Dictyota cervicornis <40% Dictyota menstrualis <40% Polysiphonia ferulacea >60% Bare Rock <40% Hypnea spinella 40-60% Solieria filiformis >60% Caulerpa mexicana >60% Polysiphonia ferulacea <40% Sargassum spp. 40-60% Hypnea spinella 40-60% Bryopsis plumosa >60% Sargassum spp. 40-60% Botryocladia occidentalis >60% Gracilaria domingensis >60% Enteromorpha sp. 40-60% Caulerpa mexicana <40% Dictyota sp. <40% Dictyota pfaffii >60% Gracilaria blodgettii 40-60% Enteromorpha sp. 40-60% Grateloupia sp. >60% Gracilaria blodgettii 40-60% Spatoglossum schroederi 40-60% Spatoglossum schroederi 40-60% Wrangelia argus 40-60% Bryopsis plumosa <40% Gracilaria sp. >60% Wrangelia argus 40-60% Solieria filiformis <40% Cladophora sp. >60% Bryopsis pennata <40% Grateloupia sp. <40% Gracilaria damaecornis >60% Bryothamnion seaforthii >60% Agardhiella sp. >60% Agardhiella sp. Absent Bryothamnion seaforthii <40% Botryocladia occidentalis Absent Cladophora sp. <40% Gracilaria damaecornis Absent Dictyota pfaffii <40% Gracilaria sp. Absent Gracilaria domingensis Absent 1994 and October 1994 (p<0.05, Tukey post-hoc test). Taxa number per quadrat was not significantly different between months (p>0.05) but it was between seasons (p<0.05). However, this last difference was more a statistical artifact than a substantial difference in taxa number between seasons as the absolute difference in taxa number per quadrat is less than one: 7.124±0.438 (95%CI, n=89) in the rainy season versus 7.957±0.700 (95%CI, n=70) in the dry season. Instituto de Investigaciones Marinas y Costeras - INVEMAR 13

Figure 2. Seasonal and interannual dominance and diversity contrast of landscape elements at La Punta de la Loma exemplified by selected sampling months: October(16)/1994, April(24)/1994 and April(02)/1995. Figure 3. Mean dry macroalgal biomass (g) per quadrat (± 1 SD) and sampling month at La Punta de la Loma, Colombian Caribbean. 14 Boletín de Investigaciones Marinas y Costeras - Vol. 35-2006

Table 3 shows the correlation matrix between several environmental factors and sand cover. The bimodal nature of the local climate was evident in that wind velocity was inversely correlated to discharges of the Magdalena river and rain, whereas rain was positively correlated to discharges of the Magdalena river. As expected, sand cover was correlated with wind velocity, and inversely correlated with discharge from the Magdalena river. This result was reinforced the fact that sand+bare rock monthly mean cover was substantially lower in the rainy season (May to December, 4.0±2.3 S.D.) than in the dry season (January to April, 20.0±14.9 S.D.). Thus, sand intrusions were a disturbance clearly associated with the dry season (Figure 4). Table 3. Correlation matrix between several environmental factors and sand cover (relative abundance) at La Punta de La Loma. Photoperiod refers to monthly cumulative hours of day light, Magdalena refers to water volume discharge of the Magdalena River, Rain refers to total precipitation and wind refers to wind velocity, all in terms of monthly averages. Photoperiod River Rain Wind Magdalena -0.520 Rain -0.017 0.623 Wind 0.174-0.816-0.924 Sand 0.347-0.840-0.500 0.659 Figure 4. Photograph of the study area showing the intertidal algal community and sand. Some macroalgae are bleached due to desiccation and previous sand intrusions. Instituto de Investigaciones Marinas y Costeras - INVEMAR 15

DISCUSSION One of the striking features of this intertidal community is the high species diversity of macroalgae. More than 55 macroalgal species co-occur in an area of ca 600 m 2. Several hypotheses have been put forward to explain why so many species can coexist at the same time and location, exploiting the same resources (competitive exclusion principle). Intermediate physical disturbance and herbivory have been suggested as factors promoting species diversity in rocky shores (Sousa, 1984; 1985; Dean and Connell, 1987; Mengue and Branch, 2001). In this study we found that sand intrusions disturb the algal community on a regular basis, probably acting as an intermediate disturbance force promoting high diversity. Sand deposited over the macroalgal community is then washed out and rocky substrate becomes available again for algal colonization, thus avoiding dominance by few species. Herbivore pressure has not been measured at La Punta de la Loma, but herbivorous fishes, urchins, and gastropods are common and are likely to exert some top-down control on algal dynamics. Other disturbance processes, such as desiccation and wave stress, may also contribute to high local species diversity. However, from our data we support the idea that the seasonal impact of sand deposition over the intertidal community in the dry season, is a likely main mechanism controlling species diversity. Sand intrusion has been identified as a bottom-up disturbance in other rocky littoral environments in the Colombian Caribbean (Nuñez et al., 1999), as it results in freeing (space) resources. At the landscape scale taxa composition and relative dominance of biotic and abiotic elements (i.e. sand and bare rock), showed a small but definitive seasonal pulse (Figure 1). Clearly superimposed on the regular seasonal pulse, interannual differences also occur as shown in biomass and in the ordination map (Figure 1). At the quadrat scale the macroalgal community was highly variable as to overshadow seasonal differences (for those quadrats placed in the area where sand intrusions never reached), confirming findings by García (1992) for number of genera and biomass. In contrast, at the landscape scale relative dominance of landscape elements, i.e. including sand and bare rock (with consequences on absolute cover of the algal bed), showed a small but definitive seasonal pulse and interannual variability. The floristic composition related to the coastal upwelling (Bula-Meyer, 1977 and 1985) on the northern coast of the Colombian Caribbean was not expressed at La Punta de la Loma. Bula-Meyer (1985) excludes La Punta de la Loma coast line from the upwelling influence, arguing a peculiar wind regime and the influence of warm brackish water from the neighboring Ciénaga Grande de Santa Marta (Bula-Meyer, 1985, p. 13), a large coastal lagoon. Indeed no temperate or subtropical species (e.g. Porphyra) were present in the algal assemblage, and in terms of composition the marine flora from La 16 Boletín de Investigaciones Marinas y Costeras - Vol. 35-2006

Punta de la Loma was similar to other rocky intertidal shores in the Caribbean (Díaz- Pulido and Bula-Meyer, 1997). The seasonal pattern of species diversity observed in La Punta de la Loma was different to that of the adjacent area of the Tayrona National Natural Park (TNNP). Macroalgal communities were more diverse in the rainy season (e.g. October) than in the dry, upwelling season (e.g. April) at the study site, while at the TNNP macroalgal communities from coral reefs (Díaz-Pulido and Garzón-Ferreira, 2002), sand plains (Bula-Meyer, 2001) and sea grass beds (Rangel, 2005), are more diverse during the dry, upwelling season. This illustrates the large variability in the dynamics of algal communities in the Colombian Caribbean region. The seasonal variability (depending on the spatial scale of observation, the landscape or the quadrat) modified by interannual changes demonstrated that if we are to understand intertidal community dynamics, several spatial and temporal scales need to be considered. ACKNOWLEDGEMENTS Many thanks to the botany students (1992-1993) of the Universidad de Bogotá Jorge Tadeo Lozano, Santa Marta, for collecting part of the material, and to Iovana Moreno and Claudia Arango who helped in the field. LITERATURE CITED Brattström, H. 1980. Rocky-shore zonation in the Santa Marta area, Colombia. Sarsia, 65: 163-226. Bula-Meyer, G. 1977. Algas marinas bénticas indicadoras de un área afectada por aguas de surgencia frente a la costa Caribe de Colombia. An. Inst. Invest. Mar. Punta de Betín, 9: 45-71. Bula-Meyer, G. 1985. Un núcleo nuevo de surgencia en el Caribe Colombiano detectado en correlación con las macroalgas. Bol. Ecotropica, 12: 3-25. Bula-Meyer, G. 2001. Ecología de las macroalgas del plano arenoso contiguo al talud de los sistemas coralinos con énfasis en el Caribe. Rev. Ac. Col. Cien. Exac., Fís. y Nat., 25:495-507. Clarke, K.R. and R.H. Green. 1988. Statistical design and analysis of ìbiological effectsî study. Mar. Ecol. Prog. Ser., 92: 213-226. Dean, R.L. and J. Connell. 1987. Marine invertebrates in an algal succession. II. Test of hypothesis to explain changes in diversity with succession. J. Exp. Mar. Biol. Ecol., 109: 217-247. Díaz-Pulido, G. and G. Bula-Meyer. 1997. Marine algae from oceanic atolls in the Southwestern Caribbean (Albuquerque Cays, Courtown Cays, Serrana Bank, and Roncador Bank). Atoll Res. Bull., 448: 1-18. Díaz-Pulido, G. and J.M. Díaz. 1997. Algal assemblages in lagoonal reefs of Caribbean oceanic atolls. Proceedings of the Eighth International Coral Reef Symposium, Panama; 1827-832. Díaz-Pulido, G. and J. Garzón-Ferreira. 2002. Seasonality in algal assemblages on upwelling-influenced coral reefs in the Colombian Caribbean. Bot. Mar., 45: 284-292. Instituto de Investigaciones Marinas y Costeras - INVEMAR 17

Díaz-Pulido, G. and M. Díaz-Ruiz. 2003. Diversity of benthic marine algae of the Colombian Atlantic. Biota Colombiana, 4:203-246. Erffa, A. von and J. Geister. 1976. Über ein holozänes Korallen- und Mangrovenvorkommen nahe Santa Marta, Kolumbien. Mitt. Inst. Colombo-Alemán Invest. Cient,. 8: 165-186. Fajardo, G.E. 1979. Surgencia costera en las proximidades de la Península de la Guajira. Bol. Cient. CIOH, 2: 7-19. Field, J.G, K.R. Clarke, and R.M. Warwick. 1982. A practical strategy for analysing multispecies distribution patterns. Mar. Ecol. Prog. Ser., 8: 37-52. García, C.B. 1992. Estacionalidad de una comunidad algal intermareal en la region de Santa Marta, Caribe Colombiano: primeros resultados. In: Memorias VIII Seminario Nacional de Ciencias y Tecnologías del Mar, Santa Marta, Octubre 1992, pp. 601-605. CCO-Colciencias. Guillot, G. and G. Márquez. 1978. Estudios en la vegetación béntica marina del Parque Nacional Natural Tayrona, costa Caribe Colombiana, I: relaciones vegetación-zonación-sustrato. An. Inst. Inv. Mar. Punta de Betín, 10: 133-148. Lambshead, P.J., H.M. Platt and K.M. Shaw. 1983. The detection of differences among assemblages of marine benthic species based on an assessment of dominance and diversity. J. Nat. Hist., 17: 859-874. Márquez, G. and G. Guillot. 1983. La vegetación marina del Parque Nacional Tayrona, costa Caribe Colombiana, II: tipos de vegetación. An. Inst. Inv. Mar. Punta de Betín, 13: 17-51. Menge, B. A., and G. M. Branch. 2001. Rocky intertidal communities: 221-252. In: M. D. Bertness, S. D. Gaines and M. E. Hay (Eds.). Marine community ecology. Sinauer Associates, Sunderland, Massachusetts. Núñez, S.G., N.H. López, C.B. García and G.R. Navas. 1999. Caracterización y comportamiento bimensual de la comunidad sésil asociada con el litoral rocoso de Bocachica, Isla Tierra Bomba, Caribe Colombiano. Cienc. Mar., 25(4): 629-646. Rangel, A. 2005. Efectos de la herbivoría en el crecimiento del pasto marino Thalassia testudinum en el Parque Nacional Natural Tayrona. Santa Marta: Tesis de Grado, Programa de Biología, Universidad del Magdalena. Salzwedell, H. and K. Müller. 1983. A summary of meteorological and hydrological data from the Bay of Santa Marta, Colombian Caribbean. An. Inst. Invest. Mar. Punta de Betín, 13: 67-83. Sousa, W.P. 1984. The role of disturbance in natural communities. Ann. Rep. Ecol. Syst., 15: 353-391. Sousa, W.P. 1985. Disturbance and patch dynamics on rocky intertidal shores: 101-124 In: S.T.A Pickett and P.S. White (Eds.). The ecology of natural disturbance and patch dynamics. Academic Press. Underwood, A. J. 2000. Experimental ecology of rocky intertidal habitats: what are we learning? J. Exp. Mar. Biol. Ecoll., 250:51-76. Underwood, A. J. and M. G. Chapman. 1998. Variation in algal assemblages on wave-exposed rocky shores in New South Wales. Mar. Freshw. Res., 49:241-254. DATE RECEIVED: 16/03/05 DATE ACCEPTED: 19/12/05 18 Boletín de Investigaciones Marinas y Costeras - Vol. 35-2006

Bol. Invest. Mar. Cost. 35 19-36 ISSN 0122-9761 Santa Marta, Colombia, 2006 SPATIAL AND TEMPORAL CHARACTERIZATION OF SOFT BOTTOM POLYCHAETES IN A SHALLOW TROPICAL BAY (COLOMBIAN CARIBBEAN) Angela I. Guzmán-Alvis 1, Patricia Lattig 2 and José A. Ruiz 2 1 Universidad Nacional de Colombia (sede Palmira), Carrera 32 vía La Candelaria, Palmira, Colombia. E-mail: aiguzmana@palmira.unal.edu.co 2 Instituto de Investigaciones Marinas y Costeras (INVEMAR), Cerro Punta Betín, Santa Marta, Colombia. E-mail: plattigm@yahoo.com.mx (PLM); joseanibalruiz@hotmail.com (JAR) ABSTRACT The spatial and temporal variations of the polychaete assemblages were studied within and off a shallow (10-25 m) tropical bay (Bahía de Portete). The polychaete abundances at family level and their trophic mechanisms were used for this purpose. Sediment samples were collected at six stations in this bay during the wet and dry seasons. Multivariate analysis indicated that off- Bay polychaete assemblages were different from the bay ones; this spatial variation was related to sedimentary characteristics, depth and turbid-water conditions. On the other hand, these assemblages did not show significant differences between the dry and wet seasons. The differences between these two assemblages were given specially by the Syllidae, Gonidadidae, Nephtyidae, Dorvilleidae, Ampharetidae, Sabellidae, Glyceridae, Lumbrineridae, Opheliidae and Maldanidae families, being more abundant and frequent off the bay, while Magelonidae, Cirratulidae, Cossuridae and Eulephetidae were more abundant and frequent within the bay. The first ten families were related to a higher sand content, lower organic matter content and lower turbid-water conditions; while the last four were related to higher mud percentages, higher organic matter content and higher turbid-water conditions. Trophic guilds data showed similar assemblages as described above, which differ in their feeding mechanisms; the bay stations were dominated by surface and subsurface deposit feeders showing the importance of detritus; while off-bay stations the carnivores were the dominant organisms, reflecting the high predation. In these assemblages, the trophic and taxonomic structure is more affected by the spatial variation in the physical characteristics of the water column and sediment than by the seasonal variation. KEY WORDS: Tropic, Polychaetes, Trophic groups, Taxonomic structure, Bahía de Portete. RESUMEN Caracterización espacial y temporal de los poliquetos de fondos blandos en una Bahía tropical (Caribe colombiano). Las variaciones espaciales y temporales de las asociaciones de poliquetos fueron Contribución No. 955 del Instituto de Investigaciones Marinas y Costeras INVEMAR Instituto de Investigaciones Marinas y Costeras - INVEMAR 19

estudiadas dentro y fuera de una bahía somera (10-25m) tropical (Bahía de Portete). Para este propósito se usó la abundancia de poliquetos a nivel de familia y sus mecanismos tróficos. Las muestras de sedimentos fueron colectadas en seis estaciones de ésta Bahía durante la época húmeda y seca. Los análisis multivariados indicaron que las asociaciones de poliquetos fuera de la bahía fueron diferentes de las del interior; esta variación espacial estuvo relacionada con las características sedimentarias, la profundidad y las condiciones de turbidez del agua. Por otro lado, estas asociaciones no mostraron diferencias significativas entre la época seca y húmeda. Las diferencias entre estas dos asociaciones estuvieron dadas especialmente por las familias Syllidae, Gonidadidae, Nephtyidae, Dorvilleidae, Ampharetidae, Sabellidae, Glyceridae, Lumbrineridae, Opheliidae y Maldanidae, que fueron más abundantes y frecuentes fuera de la bahía; mientras que Magelonidae, Cirratulidae, Cossuridae y Eulephetidae fueron más abundantes y frecuentes dentro de la bahía. Las primeras diez familias estuvieron relacionadas con altos contenidos de arenas, bajos contenidos de materia orgánica en el sedimento y baja turbidez en la columna de agua; mientras que las cuatro últimas estuvieron relacionadas con altos porcentajes de cienos y materia orgánica en los sedimentos y alta turbidez. Los datos de los gremios tróficos mostraron asociaciones similares a los descritos anteriormente, los que se diferencian en sus mecanismos de alimentación; en las estaciones de la bahía dominaron los alimentadores de depósito de superficie y sub-superficie mostrando la importancia del detritus; mientras que en las estaciones afuera de la bahía dominaron los carnívoros, reflejando una alta depredación. En estas asociaciones, la estructura taxonómica y trófica está más afectada por la variación espacial de las características físicas de la columna de agua y sedimento que por la variación estacional. PALABRAS CLAVE: Trópico, Poliquetos, Grupos tróficos, Estructura taxonómica, Bahía de Portete. INTRODUCTION There are many studies about the structure of sedimentary soft-bottom communities of coastal areas in temperate zones. Thus the theory related with assemblage structure is based mainly on these studies; by contrast, quantitative data from tropical areas are quite scarce (Alongi, 1990; Gray, 2002). The lack of information and the fast deterioration of tropical coastal zones make it difficult to understand and evaluate the natural - and anthropogenic- originated impact on the structure and function of these ecosystems. The distribution of benthic fauna widely varies over time and space due to the heterogeneous distributions of benthic habitats (Mistri et al., 2000). Studies carried out in temperate zone at a small scale (1º latitude) have shown that the assemblage structure varies with small depth changes (Gray, 2002); and the distribution and abundance of benthic organisms are affected by spatial variations in salinity and sediment composition (Zajac and Whitlatch, 1982; Mannino and Montagna, 1997; Gray, 2002). At an annual scale, the climate in temperate regions is markedly seasonal and hydrodynamic conditions affect the patterns of organic matter sedimentation and benthic community. There exists information favoring seasonal variations in the benthic communities in the tropics, as well as, evidence to the contrary. Parsons et al., (1995) show that the seasonal variations are small because of the relative homogeneous conditions in 20 Boletín de Investigaciones Marinas y Costeras - Vol. 35-2006

temperature and salinity, and that the changes occurring in benthic communities may be due to predation preventing space monopolization by one single species. On the other hand, Alongi (1989) shows that the climate and its effect on shallow benthos vary greatly within the tropics. The magnitude of seasonal fluctuations depends upon the distance from the equator; the habitats near equator show less seasonal variability than the tropical assemblages that are closer to the poles. For instance, in India the richness of tropical assemblages and benthic density is heavily influenced by seasonal changes in rainfall and run-off (Longhurst and Pauly, 1987; Alongi, 1990). In some Caribbean areas as Jamaica, Venezuela, Colombia, the richness and density do not change significantly with the season (Jackson, 1972; Bone and Klein, 2000; Guzmán-Alvis et al., 2001; Guzmán- Alvis and Carrasco, 2005b). However apparently there is no enough evidence describing the patterns in the tropics. The benthic infaunal communities are organized structurally, numerically and functionally in relation to gradients of resource availability, modified by interactions with other environmental factors (Pearson and Rosenberg, 1987; Wieking and Kröncke, 2005). Since the primary food source for benthos originates, with a few localized exceptions, in euphotic surface waters, food availability decreases with depth and declining current speed. Water movement driven by currents, tides, strong wind and other forces transports food particles in the water mass and causes resuspension of bottom sediments (Pearson and Rosenberg, 1987). This transport is of significant importance for the distribution of food to benthic animals. Species distribution may be seen as a response to the varying effects of these modified gradients. Such distributions are further affected, by other factors. These are, in general, physical factors contributing to the relative environmental harshness imposed on each species, e.g. sedimentary fluctuations in stability and in turbidity, salinity, oxygen, temperature and pressure. Other factors which exert effects independently of the primary gradients can be summarized as stochastic events and biotic interactions. These factors influence community distributions (Pearson and Rosenberg, 1987). We hypothesized that the structural variability of these polychaete assemblages is more affected by the spatial pattern than by the seasonal one, because the spatial heterogeneity (the coastal shape determines the hydrodynamic conditions affecting the water column characteristics and the sediment) is stronger than the seasonal variations. The purpose of this study is to determine the spatial and temporal variations in the polychaete assemblages in relation to sediment (grain size and organic matter) and water column (salinity, transparency, dissolved oxygen content, temperature) variables, measured in both seasons (dry and wet) and two different places (within and off the bay). The structural changes were evaluated according to taxa composition and trophic groups. Instituto de Investigaciones Marinas y Costeras - INVEMAR 21

STUDY AREA Bahía de Portete is located in the northeastern part of Colombia (12º07ʼN and 72º02ʼW). It has an approximate area of 125 km 2 with an average depth of 9 m and a maximum of 20 m. The Bayʼs only connection with the Caribbean Sea is a 2 km inlet (Solano, 1994). The climate of the region is regulated by the NE trade winds; during the dry season the trade winds are strong and continuous and the precipitation and temperatures are low (Dec-Apr) (Figure 1). During the wet season the winds are weak, the precipitation is high and the temperature increases (May-Nov) (Andrade, 2000). Bahía de Portete shows high salinity values (34-37), high temperatures (25-30 o C), and high turbidity in the water column (1-4 m). There is no oxygen deficiency (5-8 mg*l -1 ) (Solano, 1994); whereas water temperatures and salinities are the highest during the dry season. A coastal upwelling occurs in this area especially during the dry season (Andrade, 2000); providing a high amount of nutrients to the bay ecosystems. The bay is a diverse a) b) Figure 1. Annual rainfall (a) and air temperature (b). Dry season (Dec-Apr) and wet season (May-Nov). The values correspond to the annual media of the last 16 years. Data were taken from Instituto de Hidrología Meteorología y Estudios ambientales IDEAM (Colombia). 22 Boletín de Investigaciones Marinas y Costeras - Vol. 35-2006